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Supercon Inc. has fabricated two 200-mm. multifilamentary billets of niobium-titanium wire for winding into a magnet for GE Medical Systems' magnetic resonance imagers. The superconductors, which were prepared via the artificial pinning center process, demonstrated 'excellent piece length and high critical current densities.' In contrast, the magnets exhibited higher drift levels due, it is assumed, to higher joint resistivity, poor filament quality or flux creep.

A 0.5T, 95cm warm bore, cryogen-free superconducting magnet for whole body MRI has been developed and tested. By using Nb3Sn tape superconductor, this magnet is designed to meet the same performance requirement as existing helium cooled MRI magnets. Persistent operation with drift rate less than 0.1ppm/hour and a stable 5.6ppm field homogeneity in a 30cmx40cm cylindrical volume was achieved in October of 1992. The magnet is cooled and maintained at the temperature of about 10K by a Gifford McMahon(G-M) cryocooler. High quality images were produced by using this magnet with the 0.5T GE SIGNA magnetic resonance imaging system.